A variety of industrial processes generate aqueous waste streams containing contaminating amounts of organic compounds. For example, in the process of crude oil production from subterranean formations, a substantial amount of water may be produced. Such oil-associated water generally contains contaminating compounds which must be removed prior to releasing the water into the environment. Other sources of produced water are encountered in the refining of crude oil. Plants which process oil products are increasingly limited by federal and state regulations as to the total organic content (e.g., soluble and dispersed hydrocarbons) of effluent water.
Surfactants are commonly used in a variety of subterranean industrial processes that generate aqueous waste streams. The surfactants can be used for a number of purposes, including as emulsifying agents, non-emulsifying agents, foaming agents, defoaming agents, viscosifying (e.g., gelling) agents, dispersants, wetting agents, and the like. While a variety of surfactants have been used in subterranean operations, various problems have been associated with their use. For instance, certain surfactants used heretofore often have undesirable environmental characteristics or may be limited by strict environmental regulations in certain areas of the world.
Thus, it is desirable to treat produced water so that it can be reused for various processes or discharged without violating environmental regulatory standards, particularly such that the surfactants are removed from the produced water. Older techniques for dealing with contaminated water involved reinjection into wells or percolation through a series of treatment ponds. These methods were unacceptable due to their high costs and environmental damage. Even so, these techniques continue to be used where no economical options exist.
Accordingly, there remains a continuing need in the art for a method of treating produced water to remove surfactants and be reused or discharged into the natural environment.